J3/05-172

Date:    25 Apr 2005
To:      J3
From:    Rob James
Subject: Namelist I/O and UDDTIO

NUMBER:
TITLE: Namelist I/O and UDDTIO
KEYWORDS: namelist, UDDTIO
DEFECT TYPE:
STATUS: J3 consideration in progress

QUESTION:

Can namelist I/O ever invoke a user-defined derived-type I/O
procedure?

10.10.1.2 of Fortran 2003 (Namelist input values) implies that
namelist input cannot invoke a user-defined derived-type I/O
procedure.  It says that, for a derived-type variable, "the effect is
as if the variable represented were expanded into a sequence of scalar
list items of intrinsic data types", which would preclude any
derived-type I/O.

However, the same sentence says that this is done "in the same way
that formatted input/output list items are expanded (9.5.2)", which
would result in some effective list items of derived type.

9.5.3.6 and 9.5.3.7.2 also imply that a user-defined derived-type I/O
procedure could be invoked for a namelist group object.


ANSWER:

Yes, namelist I/O can invoke a user-defined derived-type I/O
procedure.  Edits are provided to correct this problem.


EDITS:
All edits refer to 04-007.

[244:8]   Remove "of intrinsic data types".

[244:10]  Remove "intrinsic".

[244:11]  Before "except", insert "if the item is of intrinsic type,".


SUBMITTED BY: Rob James

HISTORY: 05-172   m172 Submitted